(a) Field of the Invention
The present description relates to a thin film transistor (TFT) array panel for a liquid crystal display (LCD) or an organic light emitting display (OLED), and a manufacturing method for the same.
(b) Description of the Related Art
Liquid crystal displays (LCDs) are one of the most widely used type of flat panel displays. An LCD includes a liquid crystal (LC) layer interposed between two panels provided with field-generating electrodes. The LCD displays images by applying voltages to the field-generating electrodes to generate an electric field in the LC layer, which determines orientations of LC molecules in the LC layer to adjust polarization of incident light.
An LCD including two panels provided with field-generating electrodes, wherein one panel has a plurality of pixel electrodes in a matrix and the other has a common electrode covering the entire surface of the panel, dominates the LCD market.
The LCD displays images by applying a different voltage to each pixel electrode. For this purpose, thin film transistors (TFTs), which have three terminals to switch voltages applied to the pixel electrodes, are connected to the pixel electrodes and gate lines to transmit signals for controlling the thin film transistors and data lines. Using the gate lines and data lines formed on the thin film transistor array panel, voltages are applied to the pixel electrodes.
A TFT is a switching element for transmitting the image signals from the data line to the pixel electrode in response to scanning signals from the gate line. The TFT is applied to an active matrix organic light emitting display as a switching element for controlling respective light emitting elements.
When the size-increase trend of LCDs is considered, a material having low resistivity is desired since the lengths of the gate and data lines increase along with the LCD size. Accordingly, the gate and data lines are required to be formed with a material having low resistivity.
Ag is well-known for use in signal lines and as a conductor having low resistivity. When Ag is used in signal lines, problems caused by high resistance such as signal delay are solved.
However, Ag has its set of disadvantages. For example, it does not adhere well to inorganic or organic layer, resulting in lifting or peeling of Ag signal lines. Also, since Ag is susceptible to breakdown by an acid, Ag does not lend itself to being etched with other materials. These disadvantages make it difficult to take advantage of the low resistivity Ag offers, and present obstacles to using Ag in gate lines and data line.